Krebs and his trinity of cycles


Everyone who has ever taken biology at school has heard of the Krebs cycle, but few realize that Hans Krebs also discovered two other cycles. It is appropriate, at the centenary of his birth, to consider the circumstances and experiments that led Krebs to establish these metabolic pathways.

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Figure 1: Sir Hans Krebs on a motorized cycle.
Figure 2: The ornithine cycle.
Figure 3
Figure 4: The tricarboxylic acid (TCA) and glyoxylate cycles, formulated by Kornberg and Krebs20 in 1957.


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Kornberg, H. Krebs and his trinity of cycles. Nat Rev Mol Cell Biol 1, 225–228 (2000).

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